This invention relates to a fluid flow sensor and, in particular, to a novel and improved fluid flow sensor that employs solid state components and is compatible with and for use in systems employing such solid state components.
Fluid flow sensors are useful in a variety of applications where it is desirable to detect and respond in some way to changes in fluid flow or velocity. These applications include flow monitoring of biological liquids in medical systems, oil, fuel or air in hydraulic and engine systems, air in electrical and electronic systems and the like.
The present invention, though of potential use in any such system is particularly useful in electronic systems. Electronic systems include one or more heat generating circuit components, usually mounted on printed circuit boards. To assure that the heat does not become great enough to damage the components or materially alter their operating characteristics and, hence, the response of the system, the system is designed to enhance air flow in and around the components. In many cases the air flow is maintained by a fan. An air flow sensor is positioned in the vicinty of the components (e.g., mounted on the printed circuit board) to detect and respond to changes in air flow (e.g., failure of the fan or blockage of air flow vents) to generate a signal indicative thereof for use by a utility circuit. The utility circuit, for example, might sound an alarm and/or turn the system off.